Suspended monorail system



F. P. PETTIT May 27, 1969 SUSPENDED MONORAIL SYSTEM Sheet Filed May 31, 1966 5 mm o INVENTOR. FRANK F. PETTIT ATTORNEY F. P. PETTIT May 27, 1969 SUSPENDED MONORA IL SYSTEM Filed May 31, 1966 INVENTOR. FRANK P. PETTIT BY ATTORNEY IN VE'N TOR.

Sheet F. P. PETTIT SUSPENDED MONORAIL SYSTEM May 27, 1969 Filed May 51, 1966 FRANK V PET TIT United States Patent 3,446,158 SUSPENDED MON ORAIL SYSTEM Frank P. Pettit, Arvada, Colo., assignor to Projects General Corporation of America, Denver, Colo., a corporation of Colorado Filed May 31, 1966, Ser. No. 553,938

Int. Cl. B61b 13/04 US. Cl. 104-95 23 Claims ABSTRACT OF THE DISCLOSURE In a monorail system, a load-carrying vehicle with a hoist'car is suspended from an elevated track by drive units, each unit characterized by having an eccentrically mounted drive Wheel beneath the track which is urged upwardly under the weight of the vehicle into firm driving engagement with the track in either direction of travel; and brake units for the vehicle and hoist car are selectively braked and released under the control of a common hydraulic circuit utilized to reversibly drive the drive units and to control lifting and lowering of the hoist car.

This invention relates to monorail systems, and more particularly relates to a mine train being suspended for reversible travel from an inclined overhead rail system, specifically in such a way as to be capable of traversing linear and curved paths of travel in a safe, dependable manner.

The present invention may be best characterized by describing its use in connection with shaft mining operations wherein the shaft or tunnel is customarily inclined at a relatively steep angle and undergoes sharp changes in direction. It is highly desirable to be able to transport heavy loads in an out of the shaft, including personnel, cargo and eguipment; and therefore necessitates some means of conveyance which is capable of delivering the necessary power and traction both in driving and braking for transporting the loads in and out of the shaft; and at the same time must be capable of negotiating sharp curves in virtually any direction while being under the complete control of the operator at all times.

In accordance with the present invention an overhead rail or track is well suited for use in shaft mining operations since it can be more rigidly supported in place and not be subject to collection of foreign matter, heaving and swelling which is often the case along the lower wall surfaces or bottom of a mine shaft. In order to be effectively utilized, however, the monorail system should be completely articulated in order to negotiate sudden sharp changes in direction and be capable of establishing nonslipping, positive engagement with the overhead track both in driving and in braking; and further, it is highly advantageous to be able to effect braking directly through the drive units with positive automatic braking in the event of power loss, as well as through a separate, emergency braking unit. Moreover, the driving and braking units as well as any hoist mechanisms should derive their power from a common source and be operated through a common circuit under the direct control of the operator at all times.

It is therefore an object of the present invention to accomplish the foregoing and other features in a novel and improved overhead monorail system which is specifically adapted for use in shaft mining operations as described, as well as being readily conformable for use in other applications.

It is another object of the present invention to provide a monorail system including a traction drive unit capable of establishing non-slipping driving engagement with an 3,446,158 Patented May 27, 1969 overhead rail in either direction of travel with respect to the rail and in such a way as to be self-braking when not driven, and which further is completely articulated to traverse any gradual or sharp changes in direction.

It is a further object of the present invention to make provision for a brake assembly in a system of the type described which is capable of rapid, positive braking action without being affected by the presence of foreign matter which may collect along the rail surfaces, and is so constructed as to utilize the weight of the entire system for braking either in an uphill or downhill direction of travel.

It is a still further object of the present invention to provide a monorail system for lifting, supporting and transporting heavy loads which incorporates automatic as well as selective, independent braking in further combination with a positive, non-slipping traction drive with the drive and brake assemblies being arranged in balanced re lation to one another and to the load for most effective driving and braking in use; and further, to provide a system adapted for use in shaft mining operations specifically incorporating a mine locomotive and hoist car units which require a single power source for driving, stopping and hoisting operations all under the remote control of the operator, and is highly efiicient, safe and dependable in use and operation.

The preferred form of the present invention to be hereinafter described in more detail is designed for use in shaft mining operations, but again is adapted for other uses as will be readily apparent. In the preferred form, a monorail train consists of a locomotive with enclosed operator control section to which is connected in series one or more hoist cars all suspended for travel along an overhead rail in the form of an I-shaped beam. In shaft mining operations, characteristically the shaft or tunnel will extend inwardly on an incline with some change in vertical or horizontal direction as necessitated by conditions in the mine. The locomotive has overhead drive units and a braking assembly which most effectively utilize the weight of the entire system both in driving and selective braking, respectively, and the drive units are self-braking as well and include an automatic braking system in the event of power loss. An important feature is that the traction drive and braking units are equally effective in either direction of travel and accordingly may be con trolled by a reversible control system so that the hoist cars may be arranged in leading relation to the locomotive to enter the shaft, and for the return trip out of the tunnel may be in trailing relation to the locomotive. The drive units are characterized in particular by being respon sive to the weight and drawing power of the train to effect positive non-slipping engagement uniformly to opposite sides of the rail in either direction of travel. Also, braking units utilize the weight of suspension of the train for selective engagement with the rail surfaces, and the operator can control the drive and brake units as well as the hoist cars through a common control circuit.

The above and other objects, advantages and features will become more readily understood from a consideration of the following detailed description of a preferred form of the present invention when taken together with the accompanying drawings, in which:

FIGURE 1 is a side view of a mining locomotive andplan view of the mining locomotive FIGURE 6 is an end view of the traction drive unit shown in FIGURE 5.

FIGURE 7 is a side view of a preferred form of brake unit assembly.

FIGURE 8 is an end view of the brake unit assembly as shown in FIGURE 7; and

FIGURES 9 and 9A are schematic views of the hydraulic control circuit, in accordance with the present invention.

Referring in more detail to the drawings, there is shown in FIGURES 1 to 4 a mine train unit T broadly comprise-d of a locomotive 10 and hoist car 12 interconnected by a pull bar 13 with a universal coupling at each end to permit articulation between the units. A single hoist car 12 is shown solely for the purpose of illustration and it will be evident that two or more cars 12 may be flexibly interconnected to one another and in series to the locomotive. The locomotive 10 is defined by a cab section 15 being suspended for reversible travel along the lower surface ofan overhead track, which is in the form of an I-shaped beam 16, by means of a pair of drive unit assemblies 17 and 18 at opposite ends of the cab, and a brake assembly 19 is disposed intermediately between the drive units 17 and 18 for releasable engagement with the lower surface of the track. The cab may be sufliciently large to accommodate passengers, equipment or cargo and has an operator control compartment 20 at one end and may be suitably provided with front and rear access doors 21, not shown, at opposite ends. A power transmission system is represented at 22 and is enclosed within a compartment extending along the base of the cab. In turn, the hoist car 12 may be sufliciently large to carry passengers, equipment and cargo into and out of the mine shaft, and is characterized by being releasably suspended beneath a drawbar arrangement 23, the latter being guided on the track by upper follower wheel assemblies 24 and 25 with an emergency braking unit 19' positioned between the units 24 and 25. The drawbar 23 includes a remote-controlled hoist apparatus 28 for lifting and lowering the hoist car along with releasable latch members 30 to support the car from the drawbar when in the raised position.

Although the detailed construction and configuration of the locomotive cab and hoist cars form no part of the present invention, the locomotive as shown is of generally rectangular or box-like configuration with a heavy-duty rigid frame structure to permit suspension by the traction drive units 17 and 18 from the track. The drive units 17 and 18 are identical and are mounted in a corresponding manner to the upper surface of the cab for suspension from lower horizontal flange portion 32 of the track 16, the flange defining spaced, upper running surfaces and a lower opposed running surface.

Each of the drive unit assemblies 17 and 18 consists of a pair of drive units and 42 connected in swivelled relation to opposite ends of a common assembly support arm 43 which in turn is connected in swivelled relation about its center to the upper surface of the cab. Referring to FIGURES 5 and 6, each drive unit 40 and 42 of the assembly is also identical and each is broadly formed to include upper spaced pairs of flanged, rubber-covered traction wheels 44 engaging the upper running surfaces of the flange on opposite sides of the beam 16. A lower rubber-covered drive wheel 45 engages the underside of the flange 32 at a point intermediately between the traction wheels 44 but in ofiset relation to the center point between the wheels and is rotatably driven in either direction of rotation under the influence of a reversible hydraulic drive motor 46. In order to effect non-slipping, positive engagement of both the traction wheels and drive wheel against opposite surfaces of the flange portion, the weight of the locomotive is carried through the assembly support arm 43 to an eccentrically disposed shaft member 48 which serves as a common means of pivotal support for eccentric supports arms 50 and a drive wheel suspension frame 54. The arms 50 depend downwardly from a pivotal axis 51 with connecting links 52 for each of the upper traction wheel pairs, and the drive wheel suspension frame 54 supports the drive wheel 45 to follow the movement of the support arms 50 about the pivot point 51. It will be noted that the axis of rotation of drive wheel 45 and the axis of the supporting shaft 48 are disposed in horizontally offset relation on opposite sides of a vertical reference plane P through the pivotal axis 51 and which reference plane is perpendicular to the connecting link 52. As a result, the vertical weight of the locomotive when applied through the transverse shaft 48 will tend to urge the main support arm downwardly toward a vertical attitude about its point of pivotal suspension from the connecting link 52 thereby tending to urge the drive wheel upwardly and away from the reference plane P into firm engagement with the undersurface of the flange 32. In either direction of travel, because of the eccentricity of the arms 50, the weight of the locomotive is applied to force the traction wheels and the drive wheel into non-slipping engagement as described since at all times the weight will act in a direction urging the eccentric support arms downwardly and the drive wheel upwardly about the pivotal axis 51 between the traction wheels.

Considering in more detail tthe particular construction and arrangement of the drive assemblies 17 and 18, each assembly support arm 43 is centrally connected in swivelled relation to the upper surface of the cab and specifically is free to swivel about mutually perpendicular intersecting axes through post 56 which in turn is supported by a cross pin 57 the latter being journaled in upstanding brackets 58 on the cab. Each drive unit is similarly connected to opposite ends of the support arm 43 by a hanger pin 60, the upper end of which includes a bushing 61 to receive the transverse shaft 48. The eccentric arms 50 have lower bushing end portions 62 mounted on the shaft 48 on opposite sides of the bushing 61, and upper bushing end portions 64 are supported for swinging movement about stub shafts, at the pivotal axis 51, inwardly of the connecting links and centrally between the upper traction wheels. The bushing end portions 62 and 64 on each eccentric support arm are interconnected by a relatively thick-walled side plate 65, and inwardly directed end plates 66 on the support arms terminate in inner flange portions 67 which are bolted or otherwise attached to form a unitary support arm. In addition, a forwardly inclined, tension adjusting arm portion 68 is attached to each of the side plates and each terminates in a bolt-receiving end portion 69 for connection to the suspension frame 54 now to be described.

The drive wheel suspension frame 54 is of open rectangular configuration having side arms in the form of angle irons 70 supported in spaced relation on the shaft 48, and a generally V-shaped spacer plate 72 supports the arms 70 in spaced parallel relation to one another for forward substantially horizontal extension from the shaft 48. One side arm 70 is provided with a rearwardly extending portion 74 and an outboard bearing support 75 placed over one end of the hydraulic motor. A gear reduction train including a gear 76 represented in dotted form is housed within a cover plate 78 and drivingly connected from the drive motor to the drive wheel 45 which is supported from rotation between bearing blocks 80 mounted on each of the side arms 70. It is important to note that the suspension frame is supported to follow the movement of the eccentric arm 50 by means of tension adjusting bolts 82 extending between the forward, free ends of the side arms 70 and the bolt-receiving ends 69. A compression spring 83 is positioned on each bolt member 82 beneath the side arms 70 to yieldingly urge the entire frame and drive wheel upwardly against the underside of the track 16, and each of the bolts 82 can be adjusted by a nut 84 for the purpose of regulating initial traction pressure between the drive wheel and undersurface of the track.

When the weight of the locomotive is applied to the support arms 50, their eccentricity is such that the drive wheel is constantly urged into non-slipping engagement with the undersurface of the track, and the upper traction wheels 44 are forced downwardly against the upper running surfaces of the flange 32. As a result, when the drive motors for the drive units are activated, the drive wheels will rotatably engage the undersurface of the track to advance the locomotive and cars in either direction of travel. In travel, each of the drive unit assemblies are free to pivot about mutually perpendicular intersecting axes through the central portion of the support arms 43, and each drive unit of an assembly is free to pivot about mutually perpendicular intersecting axes at opposite ends of each arm 43. In this manner, a plurality of drive unit assemblies may be arranged in closely spaced relation to provide maximum driving force for the vehicle and are completely articulated to transverse any changes in vertical or horizontal direction while maintaining positive engagement with the rail. Moreover, the drive unit assemblies can effectively serve as brake members by locking the drive motors whenever de-energized so as to lock the drive wheels against rotation while remaining in positive engagement with the track.

The brake assemblies 19 and 19' are intended primarily to be used in braking the train when not in operation or, for example, to conduct loading or hoisting operations over extended time intervals. To this end, the brake assemblies 19 and 19 are identical and in the brake assembly 19, shown in FIGURES 7 and 8, a base support frame is bolted or otherwise permanently attached to the top of the cab assembly. An upper brake shoe housing is defined by cover plates 91 and 92 bolted to opposite sides of the upper end of the frame for disposition in spaced relation on opposite sides of the lower flange portion 32 of the track and in surrounding relation to a pair of upper wedge-shaped brake shoes 94. Each of the cover plates is generally C-shaped in cross-section and has an upper housing portion closed on one side with an upper inclined brake shoe-engaging wall surface 95 and vertical end walls 96 and 97. Each brake shoe 94 is comprised of a solid cast iron block member having serrated undersurface 100 engageable with the upper surface of the flange, opposite vertical end surfaces 101 and 102 and an upper inclined surface 103 directed at an angle corresponding to the angle of inclination of the upper wall 95 of the cover plate. The brake shoes are mounted for inward extension from the upper free ends of a generally U-shaped brake shoe support member 105 having a downwardly projecting lug 106 for pivotal connection at the upper end of a linkage control mechanism. Specifically, the linkage control mechanism is comprised of a horizontal spring-supporting link 110 pivotally connected to the slotted end formed between a pair of plates 112 projecting upwardly in spaced relation from an inclined spring adjusting block 113. The block 113 is adjustably mounted on the bottom surface of the base support frame by a bolt 114 and has an upper inclined surface 115 engageable with a roller 116 at the end of the pivot link 110. The opposite end of the link 110 is pivotally connected to a vertical pivot link 118 defined by a pair of flat elongated bar members extending upwardly in spaced parallel relation for pivotal connection at their upper ends to opposite sides of the lug 106 on the support bracket 105. In this way, the wedge-shaped brake shoes are normally free to pivot in a vertical plane between opposite end walls 96 and 97 of the housing about the pivotal axes of the linkage mechanism as defined at the upper end of the vertical pivot link 118 and at opposite ends of the horizontal link member 110.

Movement of the brake shoes 94 is controlled by a hydraulic cylinder 120 pivotally attached at its lower end to the bottom surface of the base support frame and having a cylinder rod 121 extending forwardly and upwardly at an angle for pivotal connection to the vertical pivot link 118 in spaced relation beneath the lug member 106. A compression spring 122 has its lower end positioned on an upstanding lug 123 on the horizontal pivot link 110 and its upper end bears against the undersurface of a third brake shoe 124 which is slidable through a vertical sleeve 125 mounted at the upper end of the base support frame and in spaced relation beneath the undersurface of the bottom flange of the track. Normally, the upper brake shoes 94 are held in a released position, as illustrated in full in FIGURE 7 of the drawing, by hydraulic fluid under pressure supplied from the control circuit to the lower end of the cylinder thereby forcing the cylinder rod 121 outwardly to overcome spring force and to force the brake shoes upwardly in spaced relation above the lower flange portion of the track and into wedging engagement against one end 97 of the brake housing. In braking, cylinder pressure is released whereupon the spring 122 will force the cylinder rod to retract inwardly through the cylinder housing while simultaneously forcing the lower brake shoe 124 upwardly into braking engagement with the undersurface of the rail and pivoting the upper brake shoes 94 downwardly into engagement with the upper running surfaces of the flange portion 32. As the brake shoes make engagement with the track, the brake housing members and support frame are initially free to move independently of the brake shoes so that the upper surfaces 95 of the brake housing will climb or slide upwardly along the upper inclined surface of the brake shoes 94 until restrained by further independent movement when the brake shoes contact the end walls 96 of the cover plates, as shown dotted in FIGURE 7, thus placing the entire weight of the locomotive on the upper brake shoes. In moving toward the braking position, the linkage mechanism is free to pivot rearwardly and somewhat downwardly while maintaining spring pressure on the lower brake shoe 124 to force it against the undersurface of the track.

Again, in braking the locomotive as described, the brake housing members 91 and 92 are effectively lifted along the brake shoes 94 and the entire locomotive is similarly lifted so that its entire weight is applied through the brake shoes to exert brake pressure against the track and to achieve most rapid and positive braking action. As the locomotive is lifted, it will relieve the weight of suspension from the drive unit assemblies and cause the eccentric support arms 50 to tilt upwardly and to materially reduce the traction pressure of the drive wheels 45 against the track. Accordingly, when the brake assemblies 19 and 19 are activated to advance to the braking position it is not necessary to stop or brake the drive wheels.

The hoist car 12, as shown in FIGURES l, 2 and 4, is in the form of an open rectangular container having vertical suspension arms releasably connected to opposite ends of the container with an inverted T-shaped horizontal rail 132 extending between the suspension arms for releasable engagement by the latches 30. In order to raise and lower the hoist car, sheaves 134 are arranged in spaced parallel relation at the upper end of the suspension arms to receive opposite ends of a hoist line 135 which extends in opposite directions from a hoist drum 136 and is wrapped around upper sheaves 138 positioned at opposite ends of the drawbar assembly 23 in spaced relation vertically above the lower sheaves 134. The drive system for the hoist apparatus 28 consists of a gear reducer 139 coupled to a hydraulic drive motor 140 and which is controlled by the operator through the hydraulic control circuit, to be described, to reel the hoist line 135 in and out for raising and lowering the hoist car 12. The releasable latch members 30 are provided with pivotal dogs 142 to clampingly engage opposite sides of the rail member 132, and the dogs can be mechanically released by means of an operator cable 144 leading from the latch members into the operator section of the cab. Normally, the drawbar assembly and suspended hoist car 12 are supported for advancement along the track 16 by upper follower wheel assemblies 24 and 25. Here each follower wheel assembly comprises upper spaced traction wheels 146 connected at opposite ends of an assembly support arm 43' which is connected in turn through the brackets 58 on the upper surface of the drawbar assembly. The connection between the upper spaced traction wheels, support arm 43' and bracket 58' is identical to that described with reference to the drive units 40, 42, assembly support arm 43 and brackets 58 of the drive unit assemblies so as to permit complete articulation of the traction wheels 146 with respect to the support arm and of the support arm with respect to the brackets 58'. In this way, any number of hoist cars may be connected in series with additional pull bars 13 flexibly interconnecting the hoist car units, and will further enable reversible travel of the hoist cars either in leading or in trailing relation to the locomotive. Similarly, upon actuation of the brake assembly 19, the hoist car and drawbar assembly are lifted to support the entire weight of the hoist car on the upper surface of the brake shoes in the braking position.

Essentially, the power transmission system 22 is comprised of a variable displacement pump 200 which is driven by an electric motor 202 or other constant speed source for displacement and return of hydraulic fluid through a hydraulic control circuit which is common to the drive, brake and hoist units; and the hydraulic control circuit is controlled by the operator from the cab section 20 to determine both speed and direction of travel, braking in either direction, as well as lifting or lowering of the hoist apparatus 28.

In operation, reference is made to FIGURE 9 illustrating a preferred form of hydraulic control circuit for remote control of the drive unit assemblies, brake units and hoist drum. Specifically, the variable displacement pump 200 may be of the swash plate-actuated type and draws hydraulic fluid from a tank 203 through filter 204 and a fixed pressure control valve represented at 205. An exhaust line 206 with pressure relief valve 207 returns excess oil to the tank 203. The speed and direction of the pump 200 is controlled by a control lever 210 in the operator control section 20 and which lever establishes the plate angle for displacement of oil from the pump 200. A four-way, four-position, closed center control valve 212 is controlled by the operator through control lever 214 to deliver fluid under pressure either to the hydraulic drive motor 46 for each of the drive units or to the hoist drive motor 140 for the hoist drum member.

Each of the drive motors 46 is preferably a fixed displacement, reversible hydraulic motor and the drive motors are connected in parallel in the circuit through fluid conducting lines 219 and 220 for the supply and return of fluid to and from the tank. In mining operations where the overhead track extends along an inclined path of travel, it is desirable to employ the drive motors 46 as braking members. For this purpose, and assuming travel in an uphill direction, fluid under pressure is applied through valve 212 and line 219 to each of the drive motors 46 and is returned through line 220 to the suction side of the pump 200'. The fluid conducting line 220 includes a filter 222, check valve 223 together with a check valve 224 in bypass line 225; and in returning fluid through line 220 to the suction side of the pump the flow path is of course through check valve 223 and filter 222 as indicated. In order to reverse the control circuit for travel in a downhill direction of travel, the swash plate angle is reversed by control lever 210 to apply fluid under pressure from the pump through line 220 and bypass line 225 to each of the drive motors 46. The fluid is discharged from the drive motors through the conducting line 219 and main control valve 212 to the pump 200. A holding valve circuit 226, illustrated in FIGURE 9A, is positioned at the exhaust side of each drive motor 46 and includes a check valve 227 and pressure relief valve 228 in control line 219' which bypasses the check valve 227. When the line 219 acts as a fluid return line on the exhaust side of the drive motor, the check valve is closed to cause the fluid to be bypassed from the motor through the pressure relief valve 228. This valve is normally open to permit return flow of fluid through the line, provided that the pressure level in the control line 219' from the pressure side of the pump is sufficiently high to hold the pressure relief valve open. However, in the event of a pressure reduction below a predetermined level on the pressure side of the pump, the pressure relief valve will close to prevent fluid flow through the return line 219 and will automatically lock the motors and drive wheels against rotation. This condition may occur, for example, if the train overruns the selected drive speed of the motor in the downhill direction or in the event of accidental pressure loss in the hydraulic circuit, for example, due to electrical power loss. As illustrated at FIG- URE 9A, the holding valve will operate in the downhill direction only; nevertheless, holding valves may be positioned on both sides of the drive motors as a safety feature to affect automatic emergency braking in either direction of travel, in the event of accidental pressure or power loss. In addition, selective braking can be accomplished in either direction of travel by advancing the control lever 214 to set the valve 212 to the closed center position thus closing the motor drive circuit and effectively locking the drive motors 46 and drive wheels 45 against continued rotation.

To operate the hoist drum apparatus 28, the control lever 214 is shifted to advance the valve 212 to the hoist position, and again the control lever 210 may be advanced to determine the speed and direction of travel of the hoist drum in lifting or lowering the hoist car unit 12. The hoist drive motor 140 may also be of the fixed displacement type and similarly may be locked in a selected position by advancing the valve 212 to the closedcenter position. Pressure relief valves 232 and 234 are provided in the circuit to relieve excess pressure from the pump 200 or motors 46 or 140 when the valve 212 is at its closed center or stop position.

Each of the brake assemblies 19 and 19' has its hydraulic cylinder connected in parallel through a fluid conducting line 240 into the control circuit. A check valve 241 and accumulator 242 are positioned in the line 240, together with a pedal-operated, two-position valve 244 which is normally open to permit passage of fluid under pressure into each of the brake cylinders whereby to hold the brake assemblies in the released position. Here the accumulator is charged to store sufficient energy to permit successive braking and release of the brake unit assemblies; and whenever additional fluid pressure is required to charge the accumulator the valve 212 may be advanced to the neutral or stop position to increase the accumulator pressure to the desired level.

The entire system is highly economical and efiicient in use and operation. For example, the necessary electrical power may be derived from collectors 250 stationed on the upper surface of the cab assembly for operation of the constant speed electric drive motor as well as for other electrical circuits, such as, for a headlight 252 and horn 254 all controlled from a switch panel 255 in the operator section 20. Through the control levers 210 and 214, the operator can control speed, braking and direction both for drive and hoist operations, and the pedal control for the valve 244 is also located in the operator section to control the brake cylinders 120.

While a preferred form of the present invention has been set forth and described herein, it will be apparent that various modifications and changes may be made without departing from the spirit and scope of the present invention as defined by the appended claims.

What is claimed is:

1. A monorail system comprising an elevated track having upper and lower wheel-engaging surfaces, 2. loadcarrying drive vehicle including a hydraulic drive circuit,

drive units mounted in spaced relation to one another and in swivelled relation to the upper surface of said vehicle for suspension and advancement of said vehicle along the track, each drive unit having upper wheels engaging the upper wheel-engaging surface and a lower drive wheel eccentrically mounted for upward swinging movement into firm bearing engagement with the lower wheelengaging surface under the suspended weight of said vehicle, and drive means being activated by said drive circuit to rotatably advance said drive wheel along the lower wheel-engaging surface.

2. A monorail system according to claim 1 further including a brake unit mounted on the upper surface of said drive vehicle intermediately between said drive units, said brake unit including brake shoes selectively engageable with the upper wheel-engaging surface and an outer brake housing provided with upper brake shoe-engaging portions, brake releasing means within said housing being operative to normally hold said brake shoes in a raised position within said housing away from engagement with the upper wheel-engaging surface with the weight of said vehicle being suspended entirely by said drive units, and brake actuating means within said housing being operative to urge said brake shoes into braking engagement with the upper surface, said housing being forced in a direction causing said upper brake shoe-engaging surfaces upwardly along said brake shoes to raise said housing a sufiicient distance to suspend the weight of said vehicle on said brake shoes in the braking position.

3. A monorail system according to claim 2, further including a drive unit support arm for connection of a pair of drive units at opposite ends of said support arm in swivelled relation to the upper surface of said vehicle, said support arm being connected at its center to the upper surface of said vehicle for swivelled movement about mutually perpendicular, intersecting axes, and each drive unit being connected to one end of said support arm for swivelled movement about mutually perpendicular intersecting axes.

4. A monorail system according to claim 3 further including a hoist car being connected for suspension from the elevated track and in driven relation to said drive vehicle, said hoist car having an upper drawbar releasably locking said car in suspended relation, follower Wheel assemblies mounted in spaced relation to one another and in swivelled relation to the upper surface of said drawbar for suspension of said hoist car on said track, and a brake unit being mounted intermediately between said follower wheel assemblies, said brake unit corresponding to said brake unit for the drive vehicle and being activated in correlated relation to said drive vehicle brake unit to simultaneously brake said hoist car by lifting said upper brake shoe-engaging surfaces to suspend the entire weight of said hoist car on said brake shoes and to relieve the weight of suspension from said follower wheel assemblies.

5. A monorail system according to claim 4, further including a hydraulically actuated hoist drum and sheave members at opposite ends of said drawbar for selective lifting and lowering of said hoist car, and remote control means on said drive vehicle to actuate said releasable locking means on said drawbar assembly.

6. A monorail system according to claim 1 in which said reversible drive means for each of said drive units is each defined by a fixed displacement, hydraulic drive motor for each of said drive wheels connected in parallel in said reversible hydraulic drive circuit, said reversible hydraulic drive circuit further including a control valve common to each of said drive motors for selective stopping of said drive motors to brake said drive units against the lower traction surface, and a holding valve associated with each of said drive motors being operative upon reduction in fluid pressure below a predetermined pressure level automatically to stop said drive motor for braking of the respective drive units.

7. In a monorail system having an elevated track provided with upper and lower opposed wheel-engaging surfaces, a drive unit suspended on said track to support a load for travel therealong, said drive unit comprising upper wheels journaled for rotation on the upper wheel-engaging surface, eccentric support means pivotally connected to said upper wheels for downward extension at an angle to a vertical reference plane, the reference plane being perpendicular to and through the axis of pivotal connection between said support arms and said upper wheels, a load support member carried by the lower ends of the said eccentric support means, a drive wheel, a drive wheel suspension frame connected to said support means to follow the movement therealong, said suspension frame supporting said drive wheel for rotatable driving engagement against the lower wheel-engaging surface, and the load being supported in swivelled relation to said load support member to urge said eccentric support means downwardly in a direction toward the vertical reference plane and said drive wheel suspension frame upwardly in a direction to cause said drive wheel to be urged into nonslipping engagement with the lower wheel-engaging surace.

8. In a monorail system according to claim 7, said drive wheel suspension frame having one end carried by said load support member and the lower ends of said eccentric support arms, and tension adjusting means extending laterally from said eccentric support arms for connection to the opposite free end of said suspension frame with the axis of rotation of said drive wheel being normally disposed on the opposite side of the vertical reference plane to that of said eccentric support arms.

9. In a monorail system according to claim 7, said drive unit being characterized by having upper wheels journaled for rotation on opposite sides of the upper wheel-engaging surface, said eccentric support means being defined by support arms pivotally connected to said upper wheels for downward extension on opposite sides of said track with the load support member carried by the lower ends of said eccentric support arms, said eccentric support arms being urged downwardly by the load in a direction toward the vertical reference plane and said drive wheel suspension plane being urged upwardly in a direction to cause said drive wheel to be urged into non-slipping engagement with the lower wheel-engaging surface in either direction of travel of the load with respect to the track.

10. In a monorail system having an elevated track provided with upper and lower opposed wheel-engaging surfaces, a drive unit assembly suspended on said track to support a load for reversible travel along said track, said drive unit assembly comprising an assembly support arm connected in swivelled relation to said load and a pair of drive units connected in swivelled relation to opposite ends of said assembly support arm, each of said drive units comprising spaced pairs of upper wheels journaled for rotation on opposite sides of the upper surface, each pair of upper wheels on a side having a horizontal connecting link therebetween, an eccentric support arm pivotally connected to each of said connecting links intermediately between said upper wheels for downward extension at an angle to a vertical reference plane perpendicular to and through the axis of pivotal connection between said eccentric support arms and said connecting links, a transverse load support member carried at the lower ends of said eccentric support arms, a drive wheel, a drive wheel suspension frame connected at one end to said transverse load support member, said suspension frame being further supported by said eccentric support arms to support said drive wheel for rotatable driving engagement against the lower wheel-engaging surface, and the opposite ends of said assembly support arm being suspended in swivelled relation from each of said transverse load support members to urge said eccentric support arms under the weight of said load in a direction downwardly toward the vertical reference plane while forcing said drive wheels upwardly 1 1 into firm bearing engagement with the lower Wheel-engaging surface.

11. In a monorail system according to claim each of said eccentric support arms including tension adjusting arm members and a rod member at the outer free end of each of said tension adjusting arms being adjustably secured to the end of said suspension frame opposite to the end connected to said load support member, and spring means on said rod member being biased to urge the opposite end of said suspension frame in a direc tion causing said drive wheel to engage the lower wheelengaging surface.

12. In a monorail system having an elevated track provided with opposed upper and lower wheel-engaging surfaces and a vehicle normally suspended for reversible travel along said track, a brake assembly comprising a brake housing secured to the upper surface of said vehicle including an upper brake shoe-engaging surface portion and a lower base support frame attached to the upper surface of the vehicle, an upper wedge-shaped brake shoe member having an upper wedging surface complementary to the brake shoe-engaging surface portion, a linkage control mechanism mounted on said lower base frame to pivotally support said brake shoe member for movement between a released position in upper spaced relation to the upper wheel-engaging surface and a lowered braking position engaging the upper Wheel-engaging surface, brake actuating and release means associated with said linkage mechanism to selectively control movement of said brake shoe member and upper brake shoeengaging surface portion between the brake release and engaging positions whereby to cause pivotal advancement of said brake shoe member to the braking position and advancement of the upper brake shoe-engaging surface portion of said housing upwardly along the wedging surface of said brake shoe member to lift the vehicle a distance to support the weight of the vehicle on said brake shoes in the braking position.

13. In a monorail system according to claim 12, said brake assembly being further characterized by having supplementary brake actuating means between said linkage mechanism and the lower traction surface yieldably urging said wedge-shaped brake shoe member toward the braking position, and brake release means between said lower supporting frame and linkage mechanism selectively operative to overcome the force of said brake actuating means to urge said linkage mechanism into a normally released position.

14. In a monorail system according to claim 12 said brake assembly further including a lower brake shoe being movable in response to the urging of said supplementary brake actuating means into braking engagement with the lower wheel-engaging surface upon movement of said first-named brake shoe member toward the braking position.

15. In a monorail system according to claim 12 wherein said brake actuating means is defined by a compression spring, and said linkage mechanism is defined by a horizontal pivot link supporting the lower end of said compression spring, an upper brake shoe supporting member and a vertical pivot link pivotally interconnected between said horizontal pivot link and the lower end of said brake shoe supporting member, said brake releasing means being defined by a hydraulic cylinder extending between said base support frame and said vertical pivot link, and a hydraulic control circuit for selectively applying fluid under pressure to said hydraulic cylinder to force said cylinder rod in a direction overcoming spring force and urging said linkage mechanism in a direction to hold said brake shoe member in the released position.

16. In a monorail system according to claim 15, wherein said compression spring includes a brake shoe at its upper end movable intobraking engagement with the lower wheel-engaging surface upon deactivating the said brake release means, and spring adjusting means engageable with said horizontal pivot link to adjustably control the disposition of said spring in relation to the lower traction surface.

17. In a monorail system having an elevated track defined by an overhead generally I-shaped beam with a lower horizontal flange portion providing opposed upper wheel-engaging surfaces and a lower wheel-engaging surface for suspension of a vehicle for reversible travel along said track, the combination therewith of drive unit assemblies normally supporting the weight of the vehicle for advancement along'said elevated tracks, and a brake unit assembly disposed intermediately between said drive unit assemblies having a brake housing including a base support frame attached to the upper surface of the vehicle and upper spaced cover plates in spaced surrounding relation to opposite sides of the flange portion on said track, each of said cover plates including an upper inclined brake shoe-engaging surface portion in vertical spaced relation above the upper wheel-engaging surface, upper generally wedge-shaped brake shoes disposed Within said cover plate, each brake shoe including an upper inclined wedge surface complementary to the brake shoeengaging surface portion, a linkage control mechanism mounted on said lower base frame including an upper, generally U-shaped support member pivotally supporting said brake shoes for movement between an upper released position in spaced relation above the upper wheel-engaging surface and a lower braking position engaging the upper Wheel-engaging surfaces, brake actuating means between said linkage mechanism and the lower wheel-engaging surfaces being biased to yieldingly urge said upper brake shoes toward the braking position, and brake release means between said base supporting frame and linkage mechanism including means to energize said brake release means whereby to overcome said brake actuating means and urge said linkage mechanism into a normally released position, and said brake actuating means being operative upon de-energizing said brake releasing means to advance said brake member to the braking position in which the brake shoe-engaging surface portions are advanced upwardly along the complementary wedging surfaces of said brake shoes to lift the vehicle from weightsuspended relation to said drive unit assemblies and to support the weight of the vehicle on said brake shoes in the braking position.

18. A monorail system for shaft mining operations comprising an elevated track disposed for extension along an inclined path of travel downwardly through the mine shaft and the track having upper and lower opposed, continuous wheel-engaging surfaces; a mine train including a load-carrying drive vehicle having a reversible hydraulic drive circuit, drive units mounted in spaced relation to one another and in swivelled relation to the upper surface of said vehicle for suspension and advancement of said vehicle for suspension and advancement of said vehicle along the track, reversible drive motors being activated by said drive circuit to advance said drive units along the lower wheel-engaging surfaces, a hydraulically controlled brake unit mounted on the upper surface of said vehicle intermediately between said drive units, said brake unit including brake shoes selectively engageable with the wheel-engaging surfaces; and a hoist car being suspended from the elevated track in driven articulated relation to said drive vehicle, said hoist car having follower wheels mounted in spaced relation to one another and in swivelled relation to said hoist car, and a hydraulically controlled brake unit being mounted intermediately between said follower wheels, said brake unit corresponding to said brake unit for the drive vehicle and being activated in correlated relation to said drive vehicle brake unit to 5 simultaneously brake said hoist car.

19. A monorail system according to claim 18, further including a hydraulically actuated hoist drum and sheave members activated by said hydraulic drive circuit for selective lifting and lowering of said hoist car.

20. A monorail system according to claim 18, said reversible hydraulic drive circuit further including a re- 13 versible pump and control valve common to each of said drive units, said brake units and said hoist drum to selectively control speed and direction of travel, braking in either direction and lifting and lowering of said hoist car.

21. A monorail system according to claim 18, said reversible hydraulic drive circuit further including a holding valve associated with each of said reversible drive motors being operative in response to a reduction in pres sure below a predetermined pressure level automatically to close the circuit to each respective drive motor for braking said drive units.

22. A monorail system comprising a track provided with wheel-engaging surfaces, a load-carrying vehicle including hydraulically controlled drive units engageable with the wheel-engaging surfaces for advancement of said vehicle along the track, a hydraulic circuit having a reversible drive motor for each drive wheel unit, a reversible pump and control valve common to said drive motors, and a holding valve associated with each of said reversible drive motors being operative in response to a reduction in pressure in said hydraulic circuit below a predetermined pressure level automatically to close said hydraulic circuit to each respective drive motor for braking said drive wheel units.

23. A monorail system according to claim 22 in which said holding valve is positioned in the fluid return line of each drive motor and including a pressure relief valve normally set to open to permit return fluid flow through the line when the fluid pressure on the pressure side of each drive motor is above a predetermined level, and said drive motors connected in parallel in said hydraulic drive circuit.

References Cited ARTHUR L. LA POINT, Primary Examiner. HOWARD BELTRAN, Assistant Examiner.

US. Cl. X.R. 

